The present invention relates to a power supply control apparatus and an image formation apparatus capable of protecting information in processing even if power fails or an AC power supply is erroneously turned off.
Conventionally, various methods have been used for data backup of image forming devices or the like at a time of power failure. A first method is provided to back up data at the time of power failure by simultaneously using an uninterruptible power supply (UPS) and a commercial power supply. A second method is provided to perform processing for recovery by switching an AC power supply on and off by a relay based on an on/off signal of a power switch without turning off the AC power supply by the power switch, and providing a time difference between an operation of the power switch and an operating timing of the relay.
The first method (the case of using the UPS), however, cannot cope with a case where the power switch is turned off during the operation. The second method (the case where a time difference is provided between the operation of the power switch and the operating timing of the relay) cannot also cope with a case where the AC power supply itself goes off due to power failure or the like. Further, factors in that the AC power supply goes off include cases where instantaneous power failure of the commercial power supply occurs, a power cord is erroneously disconnected, or an operator erroneously turns off the power switch during operation. For example, when the AC power supply is off while data is being written in a hard disk, the data may be corrupted.
It is an object of this invention to provide a power supply control apparatus and an image formation apparatus capable of protecting data in processing with a simple and low-cost configuration when the AC power supply is erroneously turned off or power failure occurs.
The power supply control apparatus according to one aspect of this invention comprises an active filter which converts an AC voltage supplied from an AC power supply to a DC voltage, and a DCxe2x80x94DC converter which converts the DC voltage converted by the active filter to voltages at predetermined levels, and respectively supplies the voltages to a load and a load control unit that controls the load. The power supply control apparatus also comprises a power supply control unit which controls operation of the DCxe2x80x94DC converter, and a detection unit which detects disconnection of the AC power supply. The power supply control unit controls the DCxe2x80x94DC converter in order to allow the DCxe2x80x94DC converter to continue supply of the voltage to the load control unit for a predetermined time when the detection unit detects disconnection of the AC power supply.
The image formation apparatus according to another aspect of this invention comprises an image forming engine which emits laser beams corresponding to image information onto a photoreceptor to form an electrostatic latent image on the photoreceptor, forms a toner image on the electrostatic latent image, and transfers a formed toner image to a transfer sheet. The image formation apparatus also comprises an image forming engine control unit which controls the image forming engine, and an active filter which converts an AC voltage supplied from an AC power supply to a DC voltage. The image formation apparatus further comprises a DCxe2x80x94DC converter which converts the DC voltage converted by the active filter to voltages at predetermined levels and respectively supplies the voltages to the image forming engine and the image forming engine control unit, a power supply control unit which controls operation of the DCxe2x80x94DC converter, and a detection unit which detects disconnection of the AC power supply. The power supply control unit controls the DCxe2x80x94DC converter in order to allow the DCxe2x80x94DC converter to continue the supply of the voltage to the image forming engine control unit for a predetermined time when the detection unit detects disconnection of the AC power supply.
Other objects and features of this invention will become apparent from the following description with reference to the accompanying drawings.